1. Field of the Invention
The field of this invention is a robotic control system which shares autonomous and hand-controller commands.
2. Description of the Prior Art
Robotic manipulation research is still in its infancy, and present day manipulation systems (teleoperator or autonomous) suffer from many weaknesses.
Consider, for example, the teleoperator systems that are currently used in space applications. Because of the time delay in transmission of signals, terrestrial teleoperators must be predictive in sending commands to the robot. One solution is to employ teleoperation in space. This solution, however, poses many problems in cost and practicality. Moreover, if teleoperation were to be done in space (from a shuttle, for example) the time delay problem would be overcome; but then mission time would be restricted according to the study reported by Montemerlop, Merlin D., The Space Perspective: Man-Machine Redundancy in Remote Manipulator Systems, Keynote Speech, NATO Advanced Research Workshop on Robots with Redundancy: Design, Sensing & Control, June 27-July 1, 1988, Salo, Lago di Garda, Italy.
With existing technologies, autonomous systems are incapable of accommodating large un-modelled variations. Moreover, since many problems in space applications are often detected, diagnosed and solved through human on-the-spot initiative, the presence of a human in the active loop becomes imperative. See Montemerlop, Merlin D. supra. We, therefore suggest (as many others have done) that the development of systems under shared control is of paramount importance in our attempt to automate space applications.
It is our observation that much of the research in shared systems, lacks a strong theoretical flavor. Effort has been directed towards building systems and implementing shared control at the servo-level. These systems consider the teleoperator as the master, record her actions in a teleoperative device, and then directly transform them into robot commands, which finally get executed under autonomous control. See, for example, Sheridan, T. B., Telerobotics', Workshop on Shared Autonomous & Teleoperated Manipulator Control, 1988 IEEE International Conference on Robotics & Automation, Apr. 24-29, Philadelphia, PA.
The Sheridan article provides a splendid historical perspective about research in telerobotics, and many shortcomings in the scenarios described above come to light in that article. Most importantly of these shortcomings, is the absence of active human intelligence that should be involved during an integration of autonomous and teleoperator inputs. By this we mean that a theory of how to intelligently share control, prior to this invention, has not yet been firmly established. The lack of an effective shared control places the responsibility of maintaining stability squarely on the shoulders of the teleoperator. This responsibility is fine for terrestrial experiments (in nuclear power plants or for prosthetics), but not for space applications.
There exist classes of applications for which attempting to build a robotic system that is either purely teleoperative or completely autonomous may be self defeating. Such self-defeating applications include, for example, automating small batch jobs in space involving satellite maintenance and repair. The motivation of this invention is to exploit the power of each system and integrate them into a single man-machine system. Such shared systems will have the capability of accepting commands from a high level planner and/or a teleoperator, and appropriately mixing them.
Other shortcomings exhibited by our present teleoperator systems are as follows. The teleoperator, often requires explicit knowledge of the relationship between her actions and that of the robot. And, in general, it is very tiresome for the operator to impart fine motions to the robot.
A search of the prior art was done for the purpose of evaluating this invention. The results of that search are as follows:
Daggett el al., U.S. Pat. No. 4,763,05 PA1 Takita et al., U.S. Pat. No. 4,582,026 PA1 Resnick, U.S. Pat. No. 4,432,063 PA1 Guittet el al., U.S. Pat. No. 4,510,574 PA1 Maruo et al., U.S. Pat. No. 4,737,697 PA1 Inoue, U.S. Pat. No. 4,641,251
Inoue discloses a divided control system in which a main control 5 is in parallel with subcontrol units, such as units 6. Such subcontrol units are used to immediately stop the robot when an unexpected obstacle is encountered. The robot is provided with a number of such subcontrol units for individually controlling each operating portion so that a high response speed is achieved if an unexpected obstacle is encountered. See Col 2, lines 40 through 56 and FIG. 2.
Guittet et al discloses proportioning of force control between a master actuator and a slave actuator by each transmitting to a control device of the other a position and/or speed signal with a transmission delay. The transmission delays are compared and a sum of the delay times is used in a first force control loop that is supplemented by a second control loop. The system's second control loop includes a second force signal that is related to the delay times being sensed. See FIG. 6 and Column 10, lines 39 through 58 where it is described as a desire of the patent to use the most appropriate configuration of the invention, based upon the delay time summation.
Maruo et al is typical of those types of systems that employ a teaching mode and a playback mode. During the teaching mode a servo is disabled and then is enabled again in the playback mode. See the abstract.
Takita et al discloses an anticipatory control system in which each point of operation can be changed over individually on the basis of a driving control instruction for a sub-loop controller associated with each operating point. See FIG. 2 for the master controller 10 and the subloop controllers such as 11a, 11b, etc.
The Daggett et al system is typical of those that operate on a cascaded control approach in which processors are individually assigned data processing and calculation tasks. These individual processors respond to extended control and basic control as shown in FIGS. 4 and 5 and as described at Column 8, lines 37 through 48.
Resnick is of interest for its disclosure of robot control over nonprogrammed and programmed points. In summary then, none of these references are deemed of significant relevance to this invention.
We conclude this background section by putting the above-described state of the art in context with some other basic background art. In an article by Sheridan, T. B., entitled "Telerobotics", Workshop on Shared Autonomous & Teleoperated Manipulator Control, 1988 IEEE International Conference on Robotics & Automation, Apr. 24-29, Philadelphia, PA. four major areas are specified as requiring research that must be done in telerobotics. The four areas include: (i) telesensing, (ii) teleactuation, (iii) computer-aiding in control and, (iv) meta analysis of task interactions. This invention focuses on some important aspects of areas (ii) and (iv) and additionally shows how these aspects relate to each other. Such aspects are also reflected in a somewhat similar hybrid position/force task representation, used for low-level tasks, as described in an article by De Schutter J., Van Brussel H., entitled "Compliant Robot Motion, I.A. Formalism for Specifying Compliant Tasks", International Journal of Robotics Research, Vol. 7, No. 4, August 1988.